[Alhambra]

I took over an allotment where beds had been formed and the turf removed had been stacked grass side down, the stack then covered with weed control sheeting.  This would have been some three years ago.

Earlier this year I opened it up and the compost looked fine and cut off in slices.  I used it to grow tomatoes in pots, mixed with well rotted manure, in the greenhouse and to earth up my potatoes.  The tomatoes have done well, but I have spent quite some time removing weeds and grass growing in the tomato pots.   

I had intended to use it to supplement the allotment beds but have concerns about the weed content.  My question is - how can I "sterilise" this compost?   

[New shoot]

Its quite difficult to do as a home gardener as you need heat or steam to do it.  There have been tales of near disaster on here where people have tried using the microwave 

You could try the old boys trick of spreading the soil out thinly, letting the weeds germinate, then hoeing them off. 

I had a similar stack from where I cleared the surface of my plot.  It was full of couch and all sorts.  The roots died off, but weed seeds were still there, so I spread the soil bit by bit and dealt with the weeds as they popped up. It was a tip given me by a site elder and it worked well 

[snowdrops]

Are you allowed bonfires? When I have one, I se some wood to get it really hot, then when I'm finished I cover it with my weediest soil. The fire can stay in for 4 days or the last couple did. Then I riddle it & use on the hope that I have heated the seeds & killed them.

[mumofstig]

this post could help

http://chat.allotment-garden.org/index.php?topic=106287.msg1192681#msg1192681